Welcome to the forum!
A first visit to Italy is exciting!
A few things that I don’t see mentioned above:
First- go for as many days as you can- 14-15 would be much better than 11-12. Your biggest expense will be airfare- same cost no matter how many nights you stay.
Be clear on how much time you actually have. Count your trip in NIGHTS on the ground in Italy- not days.
A 2 night stay means 1.5 days in a location- for example- you post 2 nights in Positano- that gives you 1 full day. You won’t arrive there til mid-late afternoon after multiple changes, etc- just enough time to check in, get settled, see a bit of the town and find dinner.
You don’t have time for Capri and Amalfi and Ravello. Choose one or add nights.
TBH I would not stay in Positano. Amalfi is the transportation hub and if you’ve read any of the posts here about visiting the AC you will now know that transportation along the coast can be brutal, time consuming and weather dependent.
Do your kids like high end shopping? That is what you will find in Positano- along with hordes of tourists, thousands of steep steps and overpriced cafes. It’s very pretty from the water though. The beach there is not a sandy beach- it is very tiny and rocky.
You mention several times how much you like wine country/visiting wineries so make that a priority.
If you rent a car you will need a designated driver if you are going to drink even a little bit of wine. The alcohol limits in Italy are even less than in USA.
A solution to this is to hire a driver or take a guided tour where all of you can enjoy the views and countryside and wineries. Driver misses out on a lot and navigator does as well.
Another solution is to just do your tasting in town where you are staying when you are not driving- lots of opportunities for this in Montepulciano, Pienza, Montalcino.
I’m going to suggest you skip the AC this trip- it’s just such a pain to navigate transportation, travel time is not quick- getting there and leaving there. With a short trip like yours (if you stick with 10-12 days you will use up 2 full days on that transportation alone).
Venice has lots of water, Venice has a real beach with sand. Venice is the most unique city in the world and makes a super great place to get over jet lag.
There’s a reason many first trips are the “Holy Trinity”- Venice- Florence- Rome. Travel is easy and each city has different types of things to see and do.
Fly into Venice
Venice 3 nights- take a vaporetto out to Burano, Torcello or spend a day at Lido.
Train to Florence- fast, direct
Florence 2 nights- pick 2 or 3 important things and don’t feel you have to visit every museum- there are dozens in Florence. We’ve been there a few times so the last visit was 4 nights- we didn’t enter a single museum.
Wander around the Oltrarno, climb the Duomo, consider a food tour, have lunch at Mercato Centrale, shop at San Lorenzo market.
The one thing I would be sure to see is The David.
Next- if you decide to pick up a car- pick up at train station or airport (airport will cost slightly more). Roberto has always provided members here with excellent direction to get out of Florence center avoiding the ZTLs. You will need a car big enough for 4 plus your luggage. Luggage should be hidden if you plan to stop anywhere en route.
We love the Val d’Orcia area for driving around. Stay in Montepulciano, Pienza or Montalcino.
Spend 3 nights here.
cont.